1. Field of the Invention
The present invention relates to a grindstone, a method of fabricating molds for fabricating optical fiber guide blocks, molds for fabricating optical fiber guide blocks, and an optical fiber guide block fabrication method, for the purpose of fabricating molds for fabricating optical fiber guide blocks capable of holding and securing the ends of optical fibers in a condition wherein their ends are positioned with high precision and secured.
2. Description of the Related Art
Optical fiber guide blocks which have optical fiber engagement portions are known as securing members for positioning and aligning multifibers at predetermined intervals with high location accuracy. In Japanese Unexamined Patent Publications Nos. Hei 6-201936 [201936/1994] and Hei 8-211244 [211244/1996], for example, optical fiber guide blocks are disclosed which are obtained by forming glass in a hot press. In Japanese Unexamined Patent Publication No. Hei 6-94945 [94945/1994] is disclosed an optical fiber guide block obtained by press-molding resin.
(1) In then past, the forming parts of optical fiber engagement portions in molds have been formed by dividing the forming surfaces a number of times and grinding a little at a time with grindstones that are very small compared to the size of the work. With this method, in addition to requiring much time for the machining, it is very difficult to make multifiber engagement portion forming, parts with high precision, and so that the cross-sectional shape is always the same shape. As a consequence, a shape is varied in configuration when observation is made about the perpendicular cross-sectional shape along the longitudinal dimension of one forming part, or when cross-sectional shapes of different forming parts are compared with each other.
(2) Also, in fabricating optical arrays, the optical fiber ends are engaged and lined up in optical fiber engagement portions in an optical fiber guide block, and pressure blocks are used to press down on and secure the optical fiber ends. In order to position and secure the optical fiber ends with high location accuracy, it is necessary that the optical fiber sides be supported, at two points by V-shaped optical fiber engagement portions in the optical fiber guide block, in a cross-section seen from a direction perpendicular to the optical axis of the optical fiber ends secured, and at one point by the pressure surface of the pressure block. In the absence of such a three-point support condition, clearances (gaps) will develop between the sides of the optical fiber, on the one hand, and the optical fiber engagement portions or the pressure surface of the pressure block, on the other hand, making it very difficult to implement holding and securing with high location accuracy.
In order to perform optical fiber end securing by the three-point support as described above, when an optical fiber is engaged in an optical fiber engagement portion, not only must the optical fiber engagement portion exhibit a shape wherewith the optical fiber can be stably engaged, but the condition must be such as to permit a portion of the side of the optical fiber to expose its crown, standing away from the optical fiber engagement portion, without being imbedded in the middle of the optical fiber engagement portion. In order to fabricate optical fiber guide blocks having the shape described above by press-molding, a specially shaped mold made to high precision is necessary. Until now, however, no such mold, nor any method for fabricating such mold, has been known.
Furthermore, if the mold can align multifiber ends with a location accuracy within the allowable range, then, on an exceptional basis, a condition wherein optical fiber crown exposure cannot be effected is permissible, but no such mold as this or method for fabricating such mold as this is known either.